A Prospective Study to Evaluate the Effectiveness of Edoxaban for the Resolution of Left Atrial Thrombosis in Patients with Atrial Fibrillation

Available evidence on left atrial (LA) thrombus dissolution in patients with atrial fibrillation (AF) largely refers to the use of vitamin K antagonist oral anticoagulants (VKAs), showing >50% thrombus resolution over a 4-week to 12-month treatment period. Available data on non-vitamin K antagonist anticoagulants (NOACs) in this setting are limited and derive from isolated case reports or observational small-sized investigations with dabigatran, rivaroxaban or apixaban. The aim of this study was to investigate the extent of thrombus resolution with edoxaban therapy in patients with AF and LA thrombosis. We conducted a prospective, observational, open-label pilot study in seven Italian institutions. We included a total of 25 patients with non-valvular AF and LA (or left atrial appendage (LAA)) thrombosis, documented by transesophageal echocardiography (TEE). All patients received edoxaban OD treatment (n = 23 on 60 mg daily; n = 2 on 30 mg daily) and underwent TEE examination after 4 weeks. The primary endpoint was the percentage of patients with complete thrombus resolution by TEE imaging at 4 weeks. The mean age of the study population was 68.3 ± 10.8 years with a female population of 16%. AF was permanent in all cases, with a mean arrhythmia duration of 4.3 ± 1.7 years. CHA(2)DS(2)-VASc and HAS-BLED scores were 3.2 ± 1.5 and 1.9 ± 1.1, respectively. We were able to demonstrate a complete thrombus resolution in 14 patients (56%) at 4 weeks. In patients with residual atrial thrombosis (n = 11), we observed a 15.4 ± 14.9% reduction in the thrombus area from baseline. As compared with patients without thrombus dissolution, those with thrombus resolution had a numerically lower-indexed LA diameter (27.9 ± 9.3 vs 34.8 ± 16.1 mm/m(2)), a smaller maximum thrombus area at baseline (45.5 ± 44.6 vs 63.9 ± 43.5 mm(2)), a higher left ventricular ejection fraction (47.4 ± 21.0% vs 38.4 ± 20.6%) and higher maximum LAA flow velocities (26.3 ± 15.2 vs 19.3 ± 10.0 cm/s). Figures on the percentage of thrombus resolution in this study are comparable to those reported in the literature for the other OACs. We conclude that, in patients with AF, the use of edoxaban is associated with a >50% resolution of atrial thrombus at 4 weeks, similar to studies using VKAs and the other NOACs (ClinicalTrials.gov identifier number: NCT034899395).